5 (c.b.) Rory's Control Group

Rory wants to know if watching the television show will have an effect on belief in aliens. He presents the show to one group and doesn’t present it to the other group. Afterwards he asks whether or not they believe in aliens. If the group who watched the show answers yes more often than the group that didn’t, he knows that watching the show will increase belief in aliens.

Rory has chosen a two-group design, which is when an experiment is done on two groups of subjects and the results are then compared. Rory is going to compare the belief in aliens of two groups: those who watched the show and those who didn't.

A two-group design almost always involves a control group and an experimental, or treatment, group. The does not get the treatment, while the treatment group does get the treatment. In Rory's case, the treatment is the television show, so the treatment group is the group that watches the show. The control group is the group that does not watch the show.

In a simple, two-group design with a control group, the researcher wants to know whether the treatment has an effect or not. Rory wants to know if watching the television show will have an effect on belief in aliens. His alien-belief survey will give him an idea of how much each group believes in aliens, and if the group who watched the show believe more, he can draw conclusions about the effect of the show.

They might be more likely to believe in the aliens to begin with. So Rory can’t know if it’s the TV show he is showing them that’s having an effect or if they were already believers. A two group design is when a research divides his or her subjects into two groups and then COMPARES their results.

A two group design almost always involves a control group and an experimental or treatment group. The control group does NOT get the treatment whereas the treatment group does get the treatment.